Inhaler for aerosolizing a dry substance by dissolving it in a solution and aerosolizing the solution

摘要

A method to make a predetermined volume of liquid available for atomization comprising: drawing liquid from a container into a metering chamber with a vacuum to fill the metering chamber with liquid and dispensing a known volume of the liquid from the metering chamber such that a known volume of the liquid is available for atomization. The above method may be carried out using, for example, an apparatus comprising: a canister (138) containing a housing (142) having an open end (144) about which a cap (146) is placed. Disposed against the open end is a washer (148), which provides a seal to prevent liquids form escaping from the housing. On top of the washer is a cylindrical member (150). The cap securely holds the cylindrical member and washer to the housing. The cylindrical member includes a cylindrical opening (151) that allows liquids to enter from the canister. The cylindrical member and the washer also serve to securely position a holding member (152) about which a compression spring (154) us disposed. The piston pump comprises a piston member (156), a cylindrical member, a valve seat (158) and a compression spring. The piston member has a frontal end (156A) and a distal end (156B) providing the valve action. The piston pump is configured such that every time the valve seat is depressed toward the canister and the released, a unit volume of liquid is dispensed through a tapered opening (161) in the valve seat. The valve seat includes a shoulder (158A), which is pressed to move the valve seat inwardly, causing it to engage with the distal end of the piston member to close the tapered opening.